# ---
# title: 1534. Count Good Triplets
# id: problem1534
# author: Tian Jun
# date: 2020-10-31
# difficulty: Easy
# categories: Array
# link: <https://leetcode.com/problems/count-good-triplets/description/>
# hidden: true
# ---
# 
# Given an array of integers `arr`, and three integers `a`, `b` and `c`. You
# need to find the number of good triplets.
# 
# A triplet `(arr[i], arr[j], arr[k])` is **good** if the following conditions
# are true:
# 
#   * `0 <= i < j < k < arr.length`
#   * `|arr[i] - arr[j]| <= a`
#   * `|arr[j] - arr[k]| <= b`
#   * `|arr[i] - arr[k]| <= c`
# 
# Where `|x|` denotes the absolute value of `x`.
# 
# Return _the number of good triplets_.
# 
# 
# 
# **Example 1:**
# 
#     
#     
#     Input: arr = [3,0,1,1,9,7], a = 7, b = 2, c = 3
#     Output: 4
#     Explanation:  There are 4 good triplets: [(3,0,1), (3,0,1), (3,1,1), (0,1,1)].
#     
# 
# **Example 2:**
# 
#     
#     
#     Input: arr = [1,1,2,2,3], a = 0, b = 0, c = 1
#     Output: 0
#     Explanation: No triplet satisfies all conditions.
#     
# 
# 
# 
# **Constraints:**
# 
#   * `3 <= arr.length <= 100`
#   * `0 <= arr[i] <= 1000`
#   * `0 <= a, b, c <= 1000`
# 
# 
## @lc code=start
using LeetCode

## add your code here:
## @lc code=end
